chiark - git - mdw - catacomb/blob - ofb-def.h

   1 /* -*-c-*-
   2  *
   3  * $Id: ofb-def.h,v 1.5 2001/06/17 00:10:51 mdw Exp $
   4  *
   5  * Definitions for output feedback mode
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: ofb-def.h,v $
  33  * Revision 1.5  2001/06/17 00:10:51  mdw
  34  * Typesetting fixes
  35  *
  36  * Revision 1.4  2001/04/03 19:36:36  mdw
  37  * Don't use @va_arg@ as an argument to @STORE32@!
  38  *
  39  * Revision 1.3  2000/06/17 11:48:02  mdw
  40  * Use secure arena for memory allocation.  Rearrange setiv slightly.
  41  *
  42  * Revision 1.2  1999/12/13 15:34:01  mdw
  43  * Add support for seeding from a generic pseudorandom source.
  44  *
  45  * Revision 1.1  1999/12/10 23:16:40  mdw
  46  * Split mode macros into interface and implementation.
  47  *
  48  */
  49
  50 #ifndef CATACOMB_OFB_DEF_H
  51 #define CATACOMB_OFB_DEF_H
  52
  53 #ifdef __cplusplus
  54   extern "C" {
  55 #endif
  56
  57 /*----- Header files ------------------------------------------------------*/
  58
  59 #include <stdarg.h>
  60 #include <string.h>
  61
  62 #include <mLib/bits.h>
  63 #include <mLib/sub.h>
  64
  65 #ifndef CATACOMB_ARENA_H
  66 #  include "arena.h"
  67 #endif
  68
  69 #ifndef CATACOMB_BLKC_H
  70 #  include "blkc.h"
  71 #endif
  72
  73 #ifndef CATACOMB_GCIPHER_H
  74 #  include "gcipher.h"
  75 #endif
  76
  77 #ifndef CATACOMB_PARANOIA_H
  78 #  include "paranoia.h"
  79 #endif
  80
  81 /*----- Macros ------------------------------------------------------------*/
  82
  83 /* --- @OFB_DEF@ --- *
  84  *
  85  * Arguments:   @PRE@, @pre@ = prefixes for the underlying block cipher
  86  *
  87  * Use:         Creates definitions for output feedback mode.
  88  */
  89
  90 #define OFB_DEF(PRE, pre)                                               \
  91                                                                         \
  92 /* --- @pre_ofbgetiv@ --- *                                             \
  93  *                                                                      \
  94  * Arguments:   @const pre_ofbctx *ctx@ = pointer to OFB context block  \
  95  *              @void *iv@ = pointer to output data block               \
  96  *                                                                      \
  97  * Returns:     ---                                                     \
  98  *                                                                      \
  99  * Use:         Reads the currently set IV.  Reading and setting an IV  \
 100  *              is not transparent to the cipher.  It will add a `step' \
 101  *              which must be matched by a similar operation during     \
 102  *              decryption.                                             \
 103  */                                                                     \
 104                                                                         \
 105 void pre##_ofbgetiv(const pre##_ofbctx *ctx, void *iv)                  \
 106 {                                                                       \
 107   octet *p = iv;                                                        \
 108   unsigned off = ctx->off;                                              \
 109   unsigned rest = PRE##_BLKSZ - off;                                    \
 110   memcpy(p, ctx->iv + off, rest);                                       \
 111   memcpy(p + rest, ctx->iv, off);                                       \
 112 }                                                                       \
 113                                                                         \
 114 /* --- @pre_ofbsetiv@ --- *                                             \
 115  *                                                                      \
 116  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 117  *              @cnost void *iv@ = pointer to IV to set                 \
 118  *                                                                      \
 119  * Returns:     ---                                                     \
 120  *                                                                      \
 121  * Use:         Sets the IV to use for subsequent encryption.           \
 122  */                                                                     \
 123                                                                         \
 124 void pre##_ofbsetiv(pre##_ofbctx *ctx, const void *iv)                  \
 125 {                                                                       \
 126   memcpy(ctx->iv, iv, PRE##_BLKSZ);                                     \
 127   ctx->off = PRE##_BLKSZ;                                               \
 128 }                                                                       \
 129                                                                         \
 130 /* --- @pre_ofbbdry@ --- *                                              \
 131  *                                                                      \
 132  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 133  *                                                                      \
 134  * Returns:     ---                                                     \
 135  *                                                                      \
 136  * Use:         Inserts a boundary during encryption.  Successful       \
 137  *              decryption must place a similar boundary.               \
 138  */                                                                     \
 139                                                                         \
 140 void pre##_ofbbdry(pre##_ofbctx *ctx)                                   \
 141 {                                                                       \
 142   uint32 niv[PRE##_BLKSZ / 4];                                          \
 143   BLKC_LOAD(PRE, niv, ctx->iv);                                         \
 144   pre##_eblk(&ctx->ctx, niv, niv);                                      \
 145   BLKC_STORE(PRE, ctx->iv, niv);                                        \
 146   ctx->off = PRE##_BLKSZ;                                               \
 147   BURN(niv);                                                            \
 148 }                                                                       \
 149                                                                         \
 150 /* --- @pre_ofbsetkey@ --- *                                            \
 151  *                                                                      \
 152  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 153  *              @const pre_ctx *k@ = pointer to cipher context          \
 154  *                                                                      \
 155  * Returns:     ---                                                     \
 156  *                                                                      \
 157  * Use:         Sets the OFB context to use a different cipher key.     \
 158  */                                                                     \
 159                                                                         \
 160 void pre##_ofbsetkey(pre##_ofbctx *ctx, const pre##_ctx *k)             \
 161 {                                                                       \
 162   ctx->ctx = *k;                                                        \
 163 }                                                                       \
 164                                                                         \
 165 /* --- @pre_ofbinit@ --- *                                              \
 166  *                                                                      \
 167  * Arguments:   @pre_ofbctx *ctx@ = pointer to cipher context           \
 168  *              @const void *key@ = pointer to the key buffer           \
 169  *              @size_t sz@ = size of the key                           \
 170  *              @const void *iv@ = pointer to initialization vector     \
 171  *                                                                      \
 172  * Returns:     ---                                                     \
 173  *                                                                      \
 174  * Use:         Initializes a OFB context ready for use.  You should    \
 175  *              ensure that the IV chosen is unique: reusing an IV will \
 176  *              compromise the security of the entire plaintext.  This  \
 177  *              is equivalent to calls to @pre_init@, @pre_ofbsetkey@   \
 178  *              and @pre_ofbsetiv@.                                     \
 179  */                                                                     \
 180                                                                         \
 181 void pre##_ofbinit(pre##_ofbctx *ctx,                                   \
 182                      const void *key, size_t sz,                        \
 183                      const void *iv)                                    \
 184 {                                                                       \
 185   static octet zero[PRE##_BLKSZ] = { 0 };                               \
 186   pre##_init(&ctx->ctx, key, sz);                                       \
 187   pre##_ofbsetiv(ctx, iv ? iv : zero);                                  \
 188 }                                                                       \
 189                                                                         \
 190 /* --- @pre_ofbencrypt@ --- *                                           \
 191  *                                                                      \
 192  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 193  *              @const void *src@ = pointer to source data              \
 194  *              @void *dest@ = pointer to destination data              \
 195  *              @size_t sz@ = size of block to be encrypted             \
 196  *                                                                      \
 197  * Returns:     ---                                                     \
 198  *                                                                      \
 199  * Use:         Encrypts or decrypts a block with a block cipher in OFB \
 200  *              mode: encryption and decryption are the same in OFB.    \
 201  *              The destination may be null to just churn the feedback  \
 202  *              round for a bit.  The source may be null to use the     \
 203  *              cipher as a random data generator.                      \
 204  */                                                                     \
 205                                                                         \
 206 void pre##_ofbencrypt(pre##_ofbctx *ctx,                                \
 207                         const void *src, void *dest,                    \
 208                         size_t sz)                                      \
 209 {                                                                       \
 210   const octet *s = src;                                                 \
 211   octet *d = dest;                                                      \
 212   unsigned off = ctx->off;                                              \
 213                                                                         \
 214   /* --- Empty blocks are trivial --- */                                \
 215                                                                         \
 216   if (!sz)                                                              \
 217     return;                                                             \
 218                                                                         \
 219   /* --- If I can deal with the block from my buffer, do that --- */    \
 220                                                                         \
 221   if (sz < PRE##_BLKSZ - off)                                           \
 222     goto small;                                                         \
 223                                                                         \
 224   /* --- Finish off what's left in my buffer --- */                     \
 225                                                                         \
 226   if (!d)                                                               \
 227     sz -= PRE##_BLKSZ - off;                                            \
 228   else {                                                                \
 229     while (off < PRE##_BLKSZ) {                                         \
 230       register octet x = s ? *s++ : 0;                                  \
 231       *d++ = ctx->iv[off++] ^ x;                                        \
 232       sz--;                                                             \
 233     }                                                                   \
 234   }                                                                     \
 235                                                                         \
 236   /* --- Main encryption loop --- */                                    \
 237                                                                         \
 238   {                                                                     \
 239     uint32 iv[PRE##_BLKSZ / 4];                                         \
 240     BLKC_LOAD(PRE, iv, ctx->iv);                                        \
 241                                                                         \
 242     for (;;) {                                                          \
 243       pre##_eblk(&ctx->ctx, iv, iv);                                    \
 244       if (sz < PRE##_BLKSZ)                                             \
 245         break;                                                          \
 246       if (d) {                                                          \
 247         if (!s)                                                         \
 248           BLKC_STORE(PRE, d, iv);                                       \
 249         else {                                                          \
 250           uint32 x[PRE##_BLKSZ / 4];                                    \
 251           BLKC_LOAD(PRE, x, s);                                         \
 252           BLKC_XSTORE(PRE, d, iv, x);                                   \
 253           s += PRE##_BLKSZ;                                             \
 254         }                                                               \
 255         d += PRE##_BLKSZ;                                               \
 256       }                                                                 \
 257       sz -= PRE##_BLKSZ;                                                \
 258     }                                                                   \
 259                                                                         \
 260     BLKC_STORE(PRE, ctx->iv, iv);                                       \
 261     off = 0;                                                            \
 262   }                                                                     \
 263                                                                         \
 264   /* --- Tidying up the tail end --- */                                 \
 265                                                                         \
 266   if (sz) {                                                             \
 267   small:                                                                \
 268     if (!d)                                                             \
 269       off += sz;                                                        \
 270     else do {                                                           \
 271       register octet x = s ? *s++ : 0;                                  \
 272       *d++ = ctx->iv[off++] ^ x;                                        \
 273       sz--;                                                             \
 274     } while (sz);                                                       \
 275   }                                                                     \
 276                                                                         \
 277   /* --- Done --- */                                                    \
 278                                                                         \
 279   ctx->off = off;                                                       \
 280   return;                                                               \
 281 }                                                                       \
 282                                                                         \
 283 /* --- Generic cipher interface --- */                                  \
 284                                                                         \
 285 static const gcipher_ops gops;                                          \
 286                                                                         \
 287 typedef struct gctx {                                                   \
 288   gcipher c;                                                            \
 289   pre##_ofbctx k;                                                       \
 290 } gctx;                                                                 \
 291                                                                         \
 292 static gcipher *ginit(const void *k, size_t sz)                         \
 293 {                                                                       \
 294   gctx *g = S_CREATE(gctx);                                             \
 295   g->c.ops = &gops;                                                     \
 296   pre##_ofbinit(&g->k, k, sz, 0);                                       \
 297   return (&g->c);                                                       \
 298 }                                                                       \
 299                                                                         \
 300 static void gencrypt(gcipher *c, const void *s, void *t, size_t sz)     \
 301 {                                                                       \
 302   gctx *g = (gctx *)c;                                                  \
 303   pre##_ofbencrypt(&g->k, s, t, sz);                                    \
 304 }                                                                       \
 305                                                                         \
 306 static void gdestroy(gcipher *c)                                        \
 307 {                                                                       \
 308   gctx *g = (gctx *)c;                                                  \
 309   BURN(*g);                                                             \
 310   S_DESTROY(g);                                                         \
 311 }                                                                       \
 312                                                                         \
 313 static void gsetiv(gcipher *c, const void *iv)                          \
 314 {                                                                       \
 315   gctx *g = (gctx *)c;                                                  \
 316   pre##_ofbsetiv(&g->k, iv);                                            \
 317 }                                                                       \
 318                                                                         \
 319 static void gbdry(gcipher *c)                                           \
 320 {                                                                       \
 321   gctx *g = (gctx *)c;                                                  \
 322   pre##_ofbbdry(&g->k);                                                 \
 323 }                                                                       \
 324                                                                         \
 325 static const gcipher_ops gops = {                                       \
 326   &pre##_ofb,                                                           \
 327   gencrypt, gencrypt, gdestroy, gsetiv, gbdry                           \
 328 };                                                                      \
 329                                                                         \
 330 const gccipher pre##_ofb = {                                            \
 331   #pre "-ofb", pre##_keysz, PRE##_BLKSZ,                                \
 332   ginit                                                                 \
 333 };                                                                      \
 334                                                                         \
 335 /* --- Generic random number generator interface --- */                 \
 336                                                                         \
 337 typedef struct grctx {                                                  \
 338   grand r;                                                              \
 339   pre##_ofbctx k;                                                       \
 340 } grctx;                                                                \
 341                                                                         \
 342 static void grdestroy(grand *r)                                         \
 343 {                                                                       \
 344   grctx *g = (grctx *)r;                                                \
 345   BURN(*g);                                                             \
 346   S_DESTROY(g);                                                         \
 347 }                                                                       \
 348                                                                         \
 349 static int grmisc(grand *r, unsigned op, ...)                           \
 350 {                                                                       \
 351   grctx *g = (grctx *)r;                                                \
 352   va_list ap;                                                           \
 353   int rc = 0;                                                           \
 354   uint32 i;                                                             \
 355   octet buf[PRE##_BLKSZ];                                               \
 356   va_start(ap, op);                                                     \
 357                                                                         \
 358   switch (op) {                                                         \
 359     case GRAND_CHECK:                                                   \
 360       switch (va_arg(ap, unsigned)) {                                   \
 361         case GRAND_CHECK:                                               \
 362         case GRAND_SEEDINT:                                             \
 363         case GRAND_SEEDUINT32:                                          \
 364         case GRAND_SEEDBLOCK:                                           \
 365         case GRAND_SEEDRAND:                                            \
 366           rc = 1;                                                       \
 367           break;                                                        \
 368         default:                                                        \
 369           rc = 0;                                                       \
 370           break;                                                        \
 371       }                                                                 \
 372       break;                                                            \
 373     case GRAND_SEEDINT:                                                 \
 374       memset(buf, 0, sizeof(buf));                                      \
 375       i = va_arg(ap, unsigned);                                         \
 376       STORE32(buf, i);                                                  \
 377       pre##_ofbsetiv(&g->k, buf);                                       \
 378       break;                                                            \
 379     case GRAND_SEEDUINT32:                                              \
 380       memset(buf, 0, sizeof(buf));                                      \
 381       i = va_arg(ap, uint32);                                           \
 382       STORE32(buf, i);                                                  \
 383       pre##_ofbsetiv(&g->k, buf);                                       \
 384       break;                                                            \
 385     case GRAND_SEEDBLOCK: {                                             \
 386       const void *p = va_arg(ap, const void *);                         \
 387       size_t sz = va_arg(ap, size_t);                                   \
 388       if (sz < sizeof(buf)) {                                           \
 389         memset(buf, 0, sizeof(buf));                                    \
 390         memcpy(buf, p, sz);                                             \
 391         p = buf;                                                        \
 392       }                                                                 \
 393       pre##_ofbsetiv(&g->k, p);                                         \
 394     } break;                                                            \
 395     case GRAND_SEEDRAND: {                                              \
 396       grand *rr = va_arg(ap, grand *);                                  \
 397       rr->ops->fill(rr, buf, sizeof(buf));                              \
 398       pre##_ofbsetiv(&g->k, buf);                                       \
 399     } break;                                                            \
 400     default:                                                            \
 401       GRAND_BADOP;                                                      \
 402       break;                                                            \
 403   }                                                                     \
 404                                                                         \
 405   va_end(ap);                                                           \
 406   return (rc);                                                          \
 407 }                                                                       \
 408                                                                         \
 409 static octet grbyte(grand *r)                                           \
 410 {                                                                       \
 411   grctx *g = (grctx *)r;                                                \
 412   octet o;                                                              \
 413   pre##_ofbencrypt(&g->k, 0, &o, 1);                                    \
 414   return (o);                                                           \
 415 }                                                                       \
 416                                                                         \
 417 static uint32 grword(grand *r)                                          \
 418 {                                                                       \
 419   grctx *g = (grctx *)r;                                                \
 420   octet b[4];                                                           \
 421   pre##_ofbencrypt(&g->k, 0, b, sizeof(b));                             \
 422   return (LOAD32(b));                                                   \
 423 }                                                                       \
 424                                                                         \
 425 static void grfill(grand *r, void *p, size_t sz)                        \
 426 {                                                                       \
 427   grctx *g = (grctx *)r;                                                \
 428   pre##_ofbencrypt(&g->k, 0, p, sz);                                    \
 429 }                                                                       \
 430                                                                         \
 431 static const grand_ops grops = {                                        \
 432   #pre "-ofb",                                                          \
 433   GRAND_CRYPTO, 0,                                                      \
 434   grmisc, grdestroy,                                                    \
 435   grword, grbyte, grword, grand_range, grfill                           \
 436 };                                                                      \
 437                                                                         \
 438 /* --- @pre_ofbrand@ --- *                                              \
 439  *                                                                      \
 440  * Arguments:   @const void *k@ = pointer to key material               \
 441  *              @size_t sz@ = size of key material                      \
 442  *                                                                      \
 443  * Returns:     Pointer to generic random number generator interface.   \
 444  *                                                                      \
 445  * Use:         Creates a random number interface wrapper around an     \
 446  *              OFB-mode block cipher.                                  \
 447  */                                                                     \
 448                                                                         \
 449 grand *pre##_ofbrand(const void *k, size_t sz)                          \
 450 {                                                                       \
 451   grctx *g = S_CREATE(grctx);                                           \
 452   g->r.ops = &grops;                                                    \
 453   pre##_ofbinit(&g->k, k, sz, 0);                                       \
 454   return (&g->r);                                                       \
 455 }                                                                       \
 456                                                                         \
 457 OFB_TEST(PRE, pre)
 458
 459 /*----- Test rig ----------------------------------------------------------*/
 460
 461 #ifdef TEST_RIG
 462
 463 #include <stdio.h>
 464
 465 #include "daftstory.h"
 466
 467 /* --- @OFB_TEST@ --- *
 468  *
 469  * Arguments:   @PRE@, @pre@ = prefixes for block cipher definitions
 470  *
 471  * Use:         Standard test rig for OFB functions.
 472  */
 473
 474 #define OFB_TEST(PRE, pre)                                              \
 475                                                                         \
 476 /* --- Initial plaintext for the test --- */                            \
 477                                                                         \
 478 static const octet text[] = TEXT;                                       \
 479                                                                         \
 480 /* --- Key and IV to use --- */                                         \
 481                                                                         \
 482 static const octet key[] = KEY;                                         \
 483 static const octet iv[] = IV;                                           \
 484                                                                         \
 485 /* --- Buffers for encryption and decryption output --- */              \
 486                                                                         \
 487 static octet ct[sizeof(text)];                                          \
 488 static octet pt[sizeof(text)];                                          \
 489                                                                         \
 490 static void hexdump(const octet *p, size_t sz)                          \
 491 {                                                                       \
 492   const octet *q = p + sz;                                              \
 493   for (sz = 0; p < q; p++, sz++) {                                      \
 494     printf("%02x", *p);                                                 \
 495     if ((sz + 1) % PRE##_BLKSZ == 0)                                    \
 496       putchar(':');                                                     \
 497   }                                                                     \
 498 }                                                                       \
 499                                                                         \
 500 int main(void)                                                          \
 501 {                                                                       \
 502   size_t sz = 0, rest;                                                  \
 503   pre##_ofbctx ctx;                                                     \
 504   int status = 0;                                                       \
 505   int done = 0;                                                         \
 506   pre##_ctx k;                                                          \
 507                                                                         \
 508   size_t keysz = PRE##_KEYSZ ?                                          \
 509     PRE##_KEYSZ : strlen((const char *)key);                            \
 510                                                                         \
 511   fputs(#pre "-ofb: ", stdout);                                         \
 512                                                                         \
 513   pre##_init(&k, key, keysz);                                           \
 514   pre##_ofbsetkey(&ctx, &k);                                            \
 515                                                                         \
 516   while (sz <= sizeof(text)) {                                          \
 517     rest = sizeof(text) - sz;                                           \
 518     memcpy(ct, text, sizeof(text));                                     \
 519     pre##_ofbsetiv(&ctx, iv);                                           \
 520     pre##_ofbencrypt(&ctx, ct, ct, sz);                                 \
 521     pre##_ofbencrypt(&ctx, ct + sz, ct + sz, rest);                     \
 522     memcpy(pt, ct, sizeof(text));                                       \
 523     pre##_ofbsetiv(&ctx, iv);                                           \
 524     pre##_ofbencrypt(&ctx, pt, pt, rest);                               \
 525     pre##_ofbencrypt(&ctx, pt + rest, pt + rest, sz);                   \
 526     if (memcmp(pt, text, sizeof(text)) == 0) {                          \
 527       done++;                                                           \
 528       if (sizeof(text) < 40 || done % 8 == 0)                           \
 529         fputc('.', stdout);                                             \
 530       if (done % 480 == 0)                                              \
 531         fputs("\n\t", stdout);                                          \
 532       fflush(stdout);                                                   \
 533     } else {                                                            \
 534       printf("\nError (sz = %lu)\n", (unsigned long)sz);                \
 535       status = 1;                                                       \
 536       printf("\tplaintext      = "); hexdump(text, sz);                 \
 537         printf(", "); hexdump(text + sz, rest);                         \
 538         fputc('\n', stdout);                                            \
 539       printf("\tciphertext     = "); hexdump(ct, sz);                   \
 540         printf(", "); hexdump(ct + sz, rest);                           \
 541         fputc('\n', stdout);                                            \
 542       printf("\trecovered text = "); hexdump(pt, sz);                   \
 543         printf(", "); hexdump(pt + sz, rest);                           \
 544         fputc('\n', stdout);                                            \
 545       fputc('\n', stdout);                                              \
 546     }                                                                   \
 547     if (sz < 63)                                                        \
 548       sz++;                                                             \
 549     else                                                                \
 550       sz += 9;                                                          \
 551   }                                                                     \
 552                                                                         \
 553   fputs(status ? " failed\n" : " ok\n", stdout);                        \
 554   return (status);                                                      \
 555 }
 556
 557 #else
 558 #  define OFB_TEST(PRE, pre)
 559 #endif
 560
 561 /*----- That's all, folks -------------------------------------------------*/
 562
 563 #ifdef __cplusplus
 564   }
 565 #endif
 566
 567 #endif